Electric arrangement with a core of magnetic material and at least one winding



1962 A. F. HOLMBE'RG EI'AL 3,068,436

ELECTRIC ARRANGEMENT WITH A CORE OF MAGNETIC MATERIAL AND AT LEAST ONE WINDING Flled Aug 20, 1957 f vg roks flaws Fkz-"pmx I /OUYBERG lV/LS BERNHHRD fiauzwsr l/ERNER Pfll/L Ram? flrromvsr United States Patent 3,068,436 ELECTRIC ARRANGEMENT WITH A CORE 0F MAGNETIC MATERIAL AND AT LEAST ONE WINDING Arne Fredrik I-Iolmberg, Stockholm Va, and Nils Bernhard Hellkvist and Werner Paul Raub, Alvsjo, Sweden, assignors to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Filed Aug. 20, 1957, Ser. No. 679,160 Claims priority, application Sweden Sept. 20, 1956 4 Claims. (Cl. 336-212) The present invention refers to an electric arrangement of a core of magnetic material, e.g. ferrite, and at least one winding, which is placed around a central part of said core. The object with the invention is to provide an electric arrangement of said kind, e.g. an inductance coil or a transformer, which for a given parallelepipedal space shows the best possible value of Q (this notion is defined in the following). In the tele technic very great demands are made upon the-characteristics of the embodied components and it has practically been shown that within this field conventional types, such as an E-formed core or a core with an outer sheath which entirely surrounds a winding, does not meet such present high demands.

The said value of Q is defined as follows:

where G signifies the cross section area of the winding,

' l signifies the average length of the layers of the winding,

An electric arrangement according to the invention is, as mentioned, constructed so that an optimum value of Q is obtained. The arrangement is characterized by the core and the wire winding together forming a mainly parallelepipedal body, the outer parts of the core being placed in the corners of the parallelepipedal body so that they form branches parallel to the mentioned central part and certain diametrical opposite peripherical parts of the wire winding ranging between the outer parts of the mentioned core standing near each other.

The invention will be described in relation to the attached drawing, where FIG. 1 shows a part of a core (the one half) and a wire winding laid in this part, FIG. 2 shows the whole core from the side, and FIG. 3 shows a modification of the arrangement according to FIG. 1.

In FIG. 1, 1 signifies the one half of the core, including a central part 12 (middle leg), four outer parts 11, which are parallel to the central part 12 and placed in the corners of a square with the side a and arms or yokes 13 arranged perpendicular to these parts, which connect the outer part 11 in question with the central part 12. The arms 13 thus form a cross, and therefore the core in this embodiment has a typical cruciform appearance. In this part of the core a circular wire winding 2 is fitted, the outer diameter of which is substantially equal to each side 3,068,436 Patented Dec. 11, 1962 ice of the square, i.e. a, whereby certain diametrical opposite and peripherical parts of the wire winding, e.g. 21, will extend between the outer parts 11 adjacent to each other.

By the entirely symmetrical formation of the core part 1 and the winding 2, diametrical opposite parts 21 and 22 of the winding 2 along two diameters perpendicular to each other will fill the space between the outer parts 11 adjacent to each other.

The height of the winding 2 is about equal totwice the height of the central part 12. After the sectioned surfaces of the parts 11 and 12, are suitably coated with an adhesive an identical part of the core 1 is placed with its central part 12 and its outer parts 11 upon the corresponding parts of the shown core part. This is shown in FIG. 2, where, however, for the sake of clearness the winding 2 has not been drawn. As is shown in the drawing, the height h of the completed core is smaller than the square side a. It can generally be said that in the parallelepipedal space, which is at disposal, the smallest dimension will constitute the height of the arrangement. This is clear from a closer studying of the magnitude Q Although the square form shown in FIG. 2 is to be preferred, the invention may be of use also with a rectangular bottom surface, such as is shown in FIG. 3, in which case the central part 12 will get an oval form. As the rectangular form is more and more accentuated, the distance between the outer edges 14 of two outer parts 11 standing near each other will be increased more and more (along the long side a of the rectangle), while the corresponding distance for one of these outer parts 11 and the remaining close standing part 111 will be decreased more and more (along the short side b of the rectangle) and will be equal to zero in a borderline case. This case is shown in FIG. 3 which shows, that the parallelepipedal form of the arrangement is still kept.

The winding 2 can, as was hereinbefore described, consist of one or many part windings, for which easily accessible terminal means 23 with soldering ears are necessary. These terminals are suitably placed, as shown in FIGS. 1 and 3, on the body of the winding 2 between the outer parts 11. Thereby the outer parallelcpipedal outline of the arrangement is preserved. In the shown forms theewinding is intended to consist of only one winding. If, for instance, it includes four part windings, four terminal means are suitably arranged, placed in four spaces between the outer parts 11 adjacent to each other, as is illustrated in FIG. 1.

We claim:

1. An electromagnetic unit comprising, in combination, a ferromagnetic core having exterior side surfaces defining an outline of substantially parallelepipedal shape having four corners and a staff shaped single central core part, a staff shaped corner part in each of said four corners of said core, each of said central core and corner parts having a longitudinal axis, all of said core and corner part axes being parallel to each other, two sets of yokes, one set of said yokes extending between one end of said corner parts and an adjacent part of said central core part and the other set of said yokes extending between the opposite end of said corner parts and the opposite end of said central core part, said pair of yokes defining four magnetic circuits with said corner and central core parts, and each one of said corner parts having a pair of intersecting experipheral outline of said core being within the outline of 5 said parallelepipedal shape 2. The combination according to claim 1 wherein said central part is of circular cross-section, the length of the longitudinal axis of said central part defining the smallest single dimension of said parallelepipedal shape.

3. The combination according to claim 1 wherein said core has a square cross-sectional outline and the height of the core is less than one side of said square.

4 4. The combination according to claim 1 wherein said core is comprised of two symmetric and complementary portions, each of said portions constituting a transverse half of the core and being encircled by said coil of Wire.

References Cited in the file of this patent UNITED STATES PATENTS 2,064,771 Vogt Dec. 15, 1936 10 2,090,991 Wohlfarth et a1 Aug. 24, 1937 2,449,434 Whitman Sept. 14, 1948 2,458,282 Maki Jan. 4, 1949 2,570,633 Barton Oct. 9, 1951 

